Sleeve patients on SSRIs lost less weight in a 68‑person matched study, with depression itself not ruled out

Many people who have bariatric surgery are also taking an antidepressant. A study published September 11 in Surgical Endoscopy asked whether one common class, selective serotonin reuptake inhibitors or SSRIs, is linked to how much weight people lose afterward. It found a gap after sleeve gastrectomy and no gap after gastric bypass, but the way the study was built leaves the central question unanswered.

Researchers at Rush University Medical Center in Chicago reviewed 799 adults who had a sleeve gastrectomy or a Roux-en-Y gastric bypass between July 2020 and June 2023. Sixty-eight of them had depression or anxiety, were taking an SSRI on its own before surgery, and stayed on it for at least 12 months afterward. The other 731 had neither condition.

The difference appeared only after statistical matching

When the researchers compared the two groups as they actually were, they found no significant difference in weight loss after either operation. That unadjusted result is worth holding onto.

The reported differences came after propensity score matching, a technique that pairs each person in one group with a similar person in the other on age, sex and clinical characteristics so the two groups look more alike on paper. After that matching, sleeve gastrectomy patients on an SSRI had lost less weight.

At 12 months they had lost 22.4 percent of their total body weight, against 28.5 percent in the matched comparison group. Measured as excess weight loss, which counts only the weight above an estimated ideal, the figures were 47.3 percent against 63.5 percent. The 3 month figures pointed the same direction.

Gastric bypass patients showed no difference

Among the gastric bypass patients there was no significant difference at any time point. The authors report p values above 0.274, meaning the numbers sat well inside the range that ordinary chance would produce.

The comparison group had no depression or anxiety

This is the limitation that governs how much the result can carry. People taking SSRIs were compared with people who had neither depression nor anxiety. They were not compared with people who had those conditions and were not taking medicine for them.

That means the study cannot separate an effect of the medicine from an effect of the condition being treated. Depression and anxiety affect sleep, appetite, physical activity and whether people keep follow-up appointments, and all of those bear on weight after surgery. The paper's title attributes the result to the SSRI. The design does not establish that.

Sixty-eight patients at a single hospital

The SSRI group held 68 people, and matching pairs each one with a single comparison patient, so the analysis rests on small numbers. It is retrospective, meaning the researchers looked back through existing records rather than planning the comparison in advance. It covers one medical center. Weight was checked at three time points across two operations, which is a number of separate comparisons, and some will cross the line for statistical significance by chance alone.

We reviewed the published abstract and the journal record. The full text sits behind a subscription, so we could not check which variables went into the matching, which specific SSRIs and doses were involved, or how patients lost to follow-up were handled.

Nothing here supports changing a prescription

A single retrospective study that cannot separate a medicine from the condition it treats is not a basis for stopping or switching an antidepressant. Stopping an SSRI without medical supervision carries its own risks. Decisions about these medicines sit with the clinician who prescribes them, and anyone weighing an operation while taking one can bring this study to their surgical team and their prescriber.